PROJECT SUMMARY/ABSTRACT Personal and group characteristics that place some individuals at higher risk of engaging in prescription drug misuse compared to their peers have been established; however, among those who misuse, researchers have not systematically discovered in-the-moment antecedents of misuse behavior in real-world environments or tracked misuse over time to understand the longer-term consequences of misuse. There is a critical need to correct these knowledge gaps because, until we do so, society's ability to prevent young adults?who display the highest misuse rates and experience increasingly costly health and well-being impacts?from misusing prescription drugs will likely remain beyond reach. The long-term goal is to reduce the occurrence of prescription drug misuse among young adults. The objective in this application is to identify factors that predict college students' misuse in the moment and determine consequences of their prescription drug misuse on health and well-being across two years. The central hypothesis is that contextual information from the moment when misuse occurs and tracking of misuse over time are crucial for understanding the immediate predictors and longer-term consequences of prescription drug misuse. The rationale for the proposed research is that understanding misuse in the moment and assessing outcomes over time will provide a strong evidence-based framework to guide targeted intervention efforts aimed at reducing this hazardous substance behavior during a developmental period deemed foundational for successful adulthood. The overall objective for this project will be attained by pursuing the following two specific aims: 1) Identify momentary factors (e.g., behaviors, emotions, situations) that predict real-time prescription drug misuse; and 2) Determine the extent to which prescription drug misuse over time alters trajectories of health and well-being outcomes. Building on the investigative team's recent preliminary data that indicate strong feasibility and utility of collecting momentary reports of prescription drug misuse in daily life, 355 individuals oversampled for elevated risk of prescription misuse will complete ecological momentary assessment (EMA) procedures for 28 days. The design consists of signal-based (scheduled across the day) and event-based (self-initiated at moments when misuse is about to occur) prompts. EMA will collect ratings of theoretically-driven contextual triggers and real-time prescription drug misuse in day-to-day environments. EMA and survey data will be collected during T1. Follow-up sessions conducted every 6 months across the next 2 years (i.e., T2, T3, T4, T5) will track prescription drug misuse over time and collect important health and well-being outcomes. Quantitative modeling will be employed to identify real-time predictors of prescription drug misuse in college students' daily lives and document how prescription drug misuse alters their developmental trajectories, accounting for other substance use and appropriate controls. These contributions will be significant because a person-focused and contextual understanding of prescription drug misuse is expected to have broad translational importance in basic and applied fields.